1. Field of the Invention
The present invention relates to air defense systems, and more particularly pertains to a single unified system that may detect, warn and even destroy airborne objects that enter restricted flight zones before the airborne objects can strike buildings, facilities or persons on the ground.
2. Description of the Prior Art
Restricted flight zones, including the so-called “no fly” zones, are often defined in terms of a geographical zone on the Earth's surface. The administration of the air space in the restricted flight zones typically requires monitoring the identity, movement, and activity of various airborne objects in the air space of the zone.
Radar systems using radio frequency waves are well known for detecting and tracking objects in the atmosphere of the Earth for the purpose of air defense. Such systems use transmitters to transmit radio waves into a selected area of the atmosphere and receivers to detect any radio waves that bounce back from a detected object within the area of transmission. Radar is used for guiding manned aircraft and unmanned weapons systems to their targets for interception, and, if necessary, for destruction. Thus, the conventional air defense systems have typically employed one system for detecting and tracking objects in the atmosphere, and a relatively separate system for destroying, or otherwise rendering ineffective, objects representing a threat to the protected ground area below the area of the atmosphere being patrolled.
Phased array radar, in which the frequency and amplitude are in phase, is a system that uses a stationary radar antenna that can transmit in one direction. The same antenna both transmits and receives radar wave signals. The degree of angle for coverage of the phased array radar can be set by the control subsystem of the radar. One precision approach radar, for example, covers 30 degrees of the horizon. Each system can be set to transmit and receive radar signals on a different frequency. Such systems are currently used by the U.S. Navy for precision approach radar on aircraft carriers, at airports, and to track missiles.
Lasers (which is an acronym for Light Amplification by the Stimulated Emission of Radiation) have been developed that employ relatively higher frequency, shorter wavelength electromagnetic radiation waves in the ultraviolet, visible and infrared region of the electromagnetic spectrum. A laser is an electro-optical device for producing a high power, monochromatic, low divergence, and coherent light source.
Different types of lasers can be employed for a transmitter, depending upon the power and wavelength of the electromagnetic wave employed in the laser system. The portion of the laser generating device where the excitation of the atoms actually occurs may be in a medium that comprises a solid, liquid, or gaseous material.
Solid state laser emissions are produced, for example, when high-voltage electricity causes a quartz flash tube to emit an intense burst of light, exciting some of the atoms in a ruby crystal to higher energy levels. At a specific energy level, some atoms emit particles of light called photons. At first, the photons are emitted in all directions. Photons from one atom stimulate emission of photons from other atoms and the light intensity is rapidly amplified. Mirrors at each end reflect the photons back and forth in the medium, continuing this process of stimulated emission and amplification. The photons leave through the partially silvered mirror at one end, and these exiting photons form the laser light emission or beam. By varying the intensity of the light source, the intensity of the laser output also can be varied.
Some of the military applications of lasers involve shooting down missiles. An example of this application occurred during a Jun. 7, 2000 test at White Sands Missile Range, N.M., in which the U.S. Army used its Tactical High Energy Laser/Advanced Concept Technology. Demonstrator (THEL/ACTD) to shoot down a rocket carrying a live warhead. The test demonstrated the first high-energy laser weapon system designed for operational use. After the rocket was launched, a fire control radar detected the rocket, tracked it with its high precision pointer tracker system, and then engaged the rocket with its high-energy chemical laser. After several seconds of having the laser beam directed on the warhead, the rocket exploded in mid-air.
The U.S. Army and Air Force also have been testing a similar airborne system using solid state lasers. The lasers may be carried by airplanes that may direct the beams at incoming missiles to destroy them, similar to the Jun. 7, 2000 test at White Sands Missile Range.
One system developed by the Raytheon Co. includes a portable tactical high energy solid state laser that may be deployed on top of Humvee personnel transport vehicles or tanks and that may generate 100 kilowatts of energy to be aimed at a specific target. Intended targets include aircraft, such as helicopters and airplanes. Further developments will attempt to increase the intensity of solid state lasers, possibly to shoot down missiles at greater distances.
The present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of providing a single unified system that may detect, track, warn and even destroy airborne objects that enter restricted flight zones without authorization, or even approach so closely to protected areas on the ground that the protected areas are in danger of damage or destruction by collision from the airborne craft.